GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.2 GNGTS 2023 lines and GNSS stations belonging to the NeVoCGNSS (Neapolitan Volcanoes Continuous GPS) network. SAR images and Method The input SAR dataset consists of images acquired by ERS 1-2, Envisat and Cosmo-SkyMed missions. The main parameters are summarized in Tab.1. InSAR analysis was performed by adopting a multi-temporal Interferometric Point Target Analysis (IPTA) approach developed in the framework of GAMMA software (Werner et al, 2003). The interferogram networks were designed by setting the thresholds for spatial and temporal baseline according to orbital tube and revisit time of each space mission. A Multi-look factor to obtain about 30m of ground resolution for all the dataset was applied and the 12m Digital Elevation Model (DEM) acquired by the TanDEM-X mission was exploited to remove the topography from the interferograms. The final solution in terms of displacement time series and linear velocity was found by Singular Value Decomposition (SVD) analysis. The reference point for all the InSAR measurements, was fixed in the proximity of the GNSS station located in Portici, named AGR1, where De Martino et al, 2021 showed a stable behaviour for a long time span with velocity value close to zero. Mission Track Time Span Incidence Angle Azimuth Angle Number of images ERS 1-2 Ascending 1993-2002 23° -14° 47 ERS 1-2 Descending 1992-2001 21° 14° 58 Envisat Ascending 2002-2010 23° -14° 62 Envisat Descending 2003-2010 21° 14° 56 CSK Ascending 2011-2021 49° -13° 603 CSK Descending 2012-2021 26° 13° 127 Tab.1: SAR dataset used in the present work Output Dataset InSAR dataset consists of 6 shapefile containing both the deformation velocity and the time series for each of the 3 space missions along ascending and descending orbit. They are collected in the INGV GeoSAR archive (http://www.geosar-iridium.ct.ingv.it/) and can be accessed and dowloaded free of charge by the following Digital Object Identifier: https://doi.org/10.13127/insar/ts21. The results in terms of Campi Flegrei ground displacement rate is shown in Fig.1. As possible to note, the deformation pattern associated with the Campi Flegrei bradyseism has a quasi semi-circular shape and is centered in the port of Pozzuoli and Rione Terra area. ERS 1-2 data (1992-2002) show a ground subsidence of the caldera consistent with the deflation phase